Chemistry of matter

 States of matter

Every element has a standard state – solid, liquid, or gas – at room temperature. The atoms of a solid fit together in a tight-knit pattern, while in a liquid the atoms are loosely connected so they flow around. In a gas, the atoms are free of each other and disperse easily. Applying heat can change the state of an element from solid to liquid, and then to gas, or even from solid to gas in some cases.

Pure forms

A pure sample of an element contains only atoms of that element. Only a few elements are found pure in nature in significant amounts. These include gold and sulfur (in the ground), and oxygen (in the air). Many elements are found in ores.

Ores

A naturally occurring substance – rock, sand, or crystal – that contains a large amount of an element is called an ore. Ores are mined so that the elements they contain can be removed. Some ores contain more than one element. The mineral malachite (right) is an ore of copper, and chemical reactions are used to extract the metal from the ore.

Compounds

Most elements do not stay pure in nature for long. Instead they react with other elements they come  into contact with, which results in the atoms of two or more elements bonding together to make an  entirely new substance called a compound. The properties of a compound are always very different to  the elements that make it.